2-Hydroxy-3-methyl-2-cyclopenten-1-one (Hmcp) is a natural compound showing many chemical similarities to hydroxypyrones, which have been tested to act as ligands during the formation of novel biologically active metal complexes. In this work, we present an experimental and theoretical study of the molecular structure of such a ligand. It has been documented, based on the total energies and the total energies partitioned into atomic contributions, that the keto–enol tautomer denoted as T1 is the most stable structure of Hmcp. This result is supported by the available structural and spectroscopic data of the studied compound. Crystallographic, vibrational (infrared and Raman), and NMR ( and chemical shifts) data are compared with the results of quantum-chemical calculations. For this purpose, we calculated the energies, geometries, frequencies and intensities of the vibrational bands as well as the chemical shifts of the studied ligand at the B3LYP/ 6-311++G(d,p) level of theory. The calculated and experimental data are in good agreement. The results of Potential Energy Distribution analysis serve as a foundation for a thorough interpretation of the vibrational spectra.